diff --git a/src/Chunk/AnvilChunk.php b/src/Chunk/AnvilChunk.php
index b612127..b0c8b9f 100644
--- a/src/Chunk/AnvilChunk.php
+++ b/src/Chunk/AnvilChunk.php
@@ -2,6 +2,7 @@
 
 namespace Aternos\Thanos\Chunk;
 
+use Aternos\Thanos\Reader\CustomCompressionReader;
 use Aternos\Thanos\Reader\LZ4BlockReader;
 use Aternos\Thanos\Reader\RawReader;
 use Aternos\Thanos\Reader\ReaderInterface;
@@ -142,6 +143,13 @@ public function __construct($file, int $offset, array $regionPosition, int $regi
                     $dataLength
                 );
                 break;
+            case 127:
+                $this->reader = new CustomCompressionReader(
+                    $this->file,
+                    $this->dataOffset,
+                    $dataLength
+                );
+                break;
             default:
                 throw new Exception("Unknown chunk compression type.");
         }
diff --git a/src/Reader/CustomCompressionReader.php b/src/Reader/CustomCompressionReader.php
new file mode 100644
index 0000000..2725871
--- /dev/null
+++ b/src/Reader/CustomCompressionReader.php
@@ -0,0 +1,47 @@
+<?php
+
+namespace Aternos\Thanos\Reader;
+
+use Exception;
+
+class CustomCompressionReader extends BufferedReader
+{
+    protected string $compressionType;
+
+    /**
+     * @inheritDoc
+     * @throws Exception
+     */
+    public function __construct($resource, int $offset, int $length)
+    {
+        parent::__construct($resource, $offset, $length);
+
+        $this->compressionType = $this->readCompressionType();
+        throw new Exception("Unsupported custom compression type: " . $this->compressionType);
+    }
+
+    /**
+     * @return string
+     * @throws Exception
+     */
+    protected function readCompressionType(): string
+    {
+        $result = "";
+        while ($char = $this->readRaw(1)) {
+            if (ord($char) !== 0) {
+                break;
+            }
+            $result .= $char;
+        }
+        return $result;
+    }
+
+    /**
+     * @inheritDoc
+     * @throws Exception
+     */
+    protected function getRawChunk(int $length): string
+    {
+        return $this->readRaw($length);
+    }
+}